SQUID sensors are well-known for use in measuring small magnetic fields or small voltages. SQUID sensors generally use one or two Josephson junctions connected in a closed superconducting loop. Generally the sensors have been designed using a toroid of superconductive materials such as niobium with a point contact junction in the toroid forming the Josephson junction. An input signal is inductively coupled to the loop through a high inductance input coil. SQUID's have also been constructed using thin film techniques in which the Josephson junctions are formed by thin film barriers. However, thin film SQUID designs heretofore proposed have presented problems in terms of obtaining favorable coupling coefficients between the input coil and the SQUID so as to achieve high energy sensitivity while maintaining large input coil inductance to achieve effective matching to external circuits. One difficulty encountered in designing an optimumly coupled thin film SQUID is the spreading inductance in the vicinity of the junctions which adds to the overall inductance of the SQUID loop with resulting decrease in signal power. The inductance of the SQUID loop cannot be effectively coupled to the signal coil and is therefore equivalent to a large leakage inductance. The second problem has been that because the SQUID loop must have a low inductance to minimize SQUID noise, it is difficult to devise a high inductance signal coil in combination with the SQUID loop.